DEC VAX/VMS 3.5 with DECnet Phase IV networking (DECnet-VAX V3.0, VMS V3.5): Revisiting "VAX/VMS Version V3.5 17-NOV-1983 16:21"

 

With substantial hand-holding by the folks at HECnet,  I managed to bring up a SimH VAX-11/780 running ancient VAX/VMS version 3.5 with DECnet Phase-IV networking running over Ethernet, learning a few things on the way.

The only two media really needed are (a) VAX/VMS 3.5 installation tape "BB-D782F-BE" and (b) DECnet license installation medium "BE-X083A-BE_-_DECNET-VAX_FULL_FUNCTION_V3.1" containing "NETRTG031.A". While exploring the latter, I learned about TU58 DECtape II, a "random-access, fixed-length-block, mass-storage tape system" from October of 1978 that "uses preformatted tape cartridges which store 262 kilobytes of data in 512-byte blocks" accessible "in a fashion similar to data stored on disks or DECtape". "A file-oriented structure is easily implemented in an operating system by setting aside several blocks on the tape to store a directory", which means its a tape that works like a very slow tiny 262 kb hard-disk!

  VAX/VMS Version V3.5 17-NOV-1983 16:21

Just to make installation simpler, I copied the installation files from both media onto a RD54 159MB Winchester hard disk using another SimH VAX. The installation session captured below uses that hard disk instead of two separate tape and TU58 media. (The installation files are also available from the FAL area of the installed VAX/VMS 3.5 node XXXV {31.42} accessible over HECnet.) It is of course possible to perform the same installation from VAX/VMS 3.5 distribution tape attached to MSA0: and DECnet license TU58 attached to TDC0:.

$ dir xxxv::
Directory XXXV::SYS$SYSDEVICE:[DECNET]
EDTCAI.SAV;1        EDTCAI1.SAV;1       LIBRARY.;1          NETACP35.EXE;1
NETRTG031.A;2       NETRTG040.A;1       NETSERVER.LOG;14    NETSERVER.LOG;13
NETSERVER.LOG;12    OPTIONAL.;1         REQUIRED.;1         VMSOPT.SAV;1
Total of 12 files.

"DECnet-VAX V3.0,  VMS V3.5" is somewhat unusual, even a little buggy. The DECnet configurator command file SYS$MANAGER:NETCONFIG.COM presents a choice of node address from the range of 1 through 1023 indicating a DECnet Phase-III implementation, but it happily accepts a Phase-IV <area>.<node> format address with no complaints:

What do you want your DECnet address to be?    [1-1023]: 31.42

This is despite support for Phase-IV style areas in the Executor characteristics. The executor can be configured with MAXIMUM AREA set to its maximum 63 with no complaints either, indicating full support of Phase-IV. Another quirk is that NCP HELP SET shows a list devoid of any SET MAXIMUM AREA, although that command works fine.

NCP>SHOW EXEC CHAR

Node Volatile Characteristics as of 18-DEC-2021 18:12:04

Executor node = 31.42 (XXXV)

Identification           = DECnet-VAX V3.0,  VMS V3.5

Management version       = V4.0.0

Incoming timer           = 45

Outgoing timer           = 45

NSP version              = V3.2.0

Maximum links            = 32

Delay factor             = 80

Delay weight             = 5

Inactivity timer         = 60

Retransmit factor        = 10

Routing version          = V2.0.0

Type                     = routing IV

Routing timer            = 600

Broadcast routing timer  = 40

Maximum address          = 1023

Maximum circuits         = 16

Maximum cost             = 1022

Maximum hops             = 30

Maximum visits           = 63

Maximum area             = 63

Max broadcast nonrouters = 64

Max broadcast routers    = 32

Area maximum cost        = 1022

Area maximum hops        = 30

Maximum buffers          = 100

Buffer size              = 576

Nonprivileged user id    = DECNET

Default access           = incoming and outgoing

Pipeline quota           = 1200

However, the DECnet implementation is clearly buggy in a negative way for DDCMP links. It does not send the Area part of it's Phase-IV address to its DDCMP peer (just sends 42 instead of 31.42). The DDCMP circuit DMC-0 for this installation had to be turned off to avoid a continuous series of operator messages as the DDCMP circuit repeatedly tries to establish adjacency using only half of the DECnet address.

It would appear the stock DECnet that shipped with VAX/VMS V3.5 was Phase-III only, and the License / Patch NETRTG031 bumps it up to DECnet Phase-IV but they forgot to upgrade and test DDCMP code as well with the patch. As a result, the patch works fine with Ethernet circuits but is broken for DDCMP circuits.

Here is the terminal session log of installation on a SimH-emulated VAX 11/780 of the ancient but very capable VAX/VMS 3.5 operating system with DECnet Phase-IV. It includes the SimH configuration file vax780.ini. A tarball of the experimental SimH instance is available for download from my gopher server or dropbox.